In the 1960’s, biologists and birding enthusiasts noted an alarming trend in osprey nests – fewer eggs were hatching, and some nests only contained shell fragments or cracked shells.  The culprit was DDT residues from chemical and pesticide use.  These toxins drained into watersheds and were ingested by fish, which were then eaten by osprey.  The hormone that controls calcium and egg thickness was distorted by these residues, resulting in a serious decline of the species.

 

The male, and female, distinguished from the male by her larger size and darker “necklace”, arrive separately in the spring and soon begin courtship.  Nests are built high above the ground, often on hydro poles or man-made nesting platforms close to water, like the ones you see here at Tiny Marsh.  These nests can be up to 1.5 metres around and anywhere from 0.5 to 2.25 metres tall!

Restrictions and bans on the use of toxic chemicals such as DDT, bird reintroduction programs, and the building of nesting poles have helped the Osprey on the road to restoring population numbers.